Search

Let s , m , n be positive integers and F be a graph. A graph G is called F -saturated if F is not a subgraph of G but G + e contain a copy of F for every edge e ∈ E (G ¯) , where G ¯ is the complement graph of G. Let s a t (n , F) be the minimum number of edges over all F -saturated graphs with order n and S a t (n , F) denotes the family of F -saturated graphs with s a t (n , F) edges and n vertices. Let m K 2 denote a matching of size m and let s K 2 f denote a fractional matching of size s. In this paper, we determine the exact value of s a t (n , m K 2) , and characterize S a t (n , m K 2) when n + 2 m < n < 3 m. Moreover, we also determine the exact value of s a t (n , s K 2 f) , and characterize S a t (n , s K 2 f) when n > 2 s. The main results provide partial answers to the open question posed by Faudree et al. (2011). [ABSTRACT FROM AUTHOR]

A 3‐graph F ${\rm{ {\mathcal F} }}$ is U(s,2s+1) $U(s,2s+1)$ if for any s $s$ edges e1,...,es∈E(F) ${e}_{1},\ldots ,{e}_{s}\in E({\rm{ {\mathcal F} }})$, ∣e1∪⋯∪es∣≤2s+1 $| {e}_{1}\cup \cdots \cup {e}_{s}| \le 2s+1$. Frankl and Kupavskii proposed the following conjecture: For any 3‐graph F ${\rm{ {\mathcal F} }}$ with n $n$ vertices, if F ${\rm{ {\mathcal F} }}$ is U(s,2s+1) $U(s,2s+1)$, then e(F)≤maxn−12,(n−s−1)s+12+s+13,2s+13. $\begin{array}{c}e({\mathscr{F}})\le \max \left\{\left(\genfrac{}{}{0ex}{}{n-1}{2}\right),(n-s-1)\left(\genfrac{}{}{0ex}{}{s+1}{2}\right)\right.\\ \,\left.+\left(\genfrac{}{}{0ex}{}{s+1}{3}\right),\left(\genfrac{}{}{0ex}{}{2s+1}{3}\right)\right\}.\end{array}$ In this paper, we confirm Frankl and Kupavskii's conjecture. [ABSTRACT FROM AUTHOR]

Background: Executive function enhancement is considered necessary for improving the quality of life of patients with neurological or psychiatric disorders, such as attention‐deficit/hyperactivity disorder, obsessive‐compulsive disorder and Alzheimer's disease. Transcranial electrical stimulation (tES) has been shown to have some beneficial effects on executive functioning, but the quantification of these improvements remains controversial. We aimed to explore the potential beneficial effects on executive functioning induced by the use of transcranial alternating current stimulation (tACS)/transcranial direct current stimulation (tDCS) on the right inferior frontal gyrus (IFG) and the accompanying brain function variations in the resting state. Methods: We recruited 229 healthy adults to participate in Experiments 1 (105 participants) and 2 (124 participants). The participants in each experiment were randomly divided into tACS, tDCS, and sham groups. The participants completed cognitive tasks to assess behavior related to three core components of executive functions. Functional near‐infrared spectroscopy (fNIRS) was used to monitor the hemodynamic changes in crucial cortical regions in the resting state. Results: Inhibition and cognitive flexibility (excluding working memory) were significantly increased after tACS/tDCS, but there were no significant behavioral differences between the tACS and tDCS groups. fNIRS revealed that tDCS induced decreases in the functional connectivity (increased neural efficiency) of the relevant cortices. Conclusions: Enhancement of executive function was observed after tES, and the beneficial effects of tACS/tDCS may need to be precisely evaluated via brain imaging indicators at rest. tDCS revealed better neural benefits than tACS during the stimulation phase. These findings might provide new insights for selecting intervention methods in future studies and for evaluating the clinical efficacy of tES. [ABSTRACT FROM AUTHOR]

Let n , m be integers such that 1 ≤ m ≤ (n − 2) / 2 and let [ n ] = { 1 , ... , n }. Let G = { G 1 , ... , G m + 1 } be a family of graphs on the same vertex set [ n ]. In this paper, we prove that if for any i ∈ [ m + 1 ] , the spectral radius of G i is not less than max ⁡ { 2 m , 1 2 (m − 1 + (m − 1) 2 + 4 m (n − m)) } , then G admits a rainbow matching, i.e. a choice of disjoint edges e i ∈ G i , unless G 1 = G 2 = ... = G m + 1 and G 1 ∈ { K 2 m + 1 ∪ (n − 2 m − 1) K 1 , K m ∨ (n − m) K 1 }. [ABSTRACT FROM AUTHOR]

For a k $k$‐uniform hypergraph H $H$, let δ1(H) ${\delta }_{1}(H)$ denote the minimum vertex degree of H $H$, and ν(H) $\nu (H)$ denote the size of the largest matching in H $H$. In this paper, we show that for any k≥3 $k\ge 3$ and β>0 $\beta \gt 0$, there exists an integer n0(β,k) ${n}_{0}(\beta ,k)$ such that for positive integers n≥n0 $n\ge {n}_{0}$ and m≤(k2(k−1)−β)nk $m\le (\frac{k}{2(k-1)}-\beta)\frac{n}{k}$, if H $H$ is an n $n$‐vertex k $k$‐graph with δ1(H)>n−1k−1−n−mk−1 ${\delta }_{1}(H)\gt \left(\genfrac{}{}{0ex}{}{n-1}{k-1}\right)-\left(\genfrac{}{}{0ex}{}{n-m}{k-1}\right)$, then ν(H)≥m $\nu (H)\ge m$. This improves upon earlier results of Bollobás, Daykin, and Erdős for the range n>2k3(m+1) $n\gt 2{k}^{3}(m+1)$ and Huang and Zhao for the range n≥3k2m $n\ge 3{k}^{2}m$. [ABSTRACT FROM AUTHOR]

Let k and n be two integers, with k ≥ 3 , n ≡ 0 (mod k) , and n sufficiently large. We determine the (k − 1) -degree threshold for the existence of a rainbow perfect matchings in n -vertex k -uniform hypergraph. This implies the result of Rödl, Ruciński, and Szemerédi on the (k − 1) -degree threshold for the existence of perfect matchings in n -vertex k -uniform hypergraphs. In our proof, we identify the extremal configurations of closeness, and consider whether or not the hypergraph is close to the extremal configuration. In addition, we also develop a novel absorbing device and generalize the absorbing lemma of Rödl, Ruciński, and Szemerédi. [ABSTRACT FROM AUTHOR]

Let G be a simple graph with the vertex set V(G) and edge set E(G). For x ∈ V (G) , let N (x) = { y ∈ V (G) | x y ∈ E (G) } and N (X) = ⋃ x ∈ X N (x) . For X ⊆ V (G) , let d (X) : = | X | - | N (X) | be the difference of X. The critical difference of G denoted by d c (G) is max { d (X) | X ⊆ V (G) } . Let α (G) and μ (G) denote the independence number and the matching number of G, respectively. We define core(G) as the intersection of all maximum independent sets in G. In this paper, we characterize graphs G, which satisfy d c (G) = α (G) - μ (G) . Furthermore, we also characterize graphs G, which satisfy d c (G) = α (G) - μ (G) = | c o r e (G) | - | N (c o r e (G)) | . Our results answer two problems proposed by Levit and Mandrescu (Graphs Comb 28:243–250, 2012; J Algebr Comb 56:59–73, 2022). [ABSTRACT FROM AUTHOR]

(1) Background--With the implementation of the natural forests total stop-logging policy, the wood raw materials provided by the state-owned forest areas in Northeast China are not enough to support the normal production of wood processing enterprises. The concentration of log and sawn timber import market in the state-owned forest area of Northeast China is too high, and the import market is mainly Russia, the United States, Canada and New Zealand. With the intensification of international trade conflicts in timber forest products, Russia, Turkey, India and other countries have restricted the export of timber resources through tariff and non-tariff measures. Different types of wood processing enterprises, especially the state-owned wood processing enterprises are facing many difficulties and need to explore the transformation strategy. (2) Methods--In this paper, private wood processing enterprises and some forestry bureaus in the stateowned forest areas of Northeast China were used as research objects and 76 valid questionnaires and 20 audio interviews were obtained by using cross-cycle and multi-level investigation methods. Firstly, the audio was converted into text data, and Nvivo12. 0 software was used for word cloud analysis based on the rooted coding theory. In this study, only concepts related to the subject of constraints on the imported timber resources were proposed. Finally, the transformation strategies of wood processing enterprises in the state-owned forest areas of Northeast China was studied and analyzed by using the modeling logic diagram formed by the above data. (3) Results--First, three core categories of resource constraints, cost control and transformation strategies are extracted from the interview records according to the coding results. Resource constraints are the core factor that affect enterprise transformation. Solving resource constraints is conducive to cost control, thus promoting enterprise transformation from different angles. Second, the restrictions on wood imports in international laws and bans and the continuous improvement of domestic ecological sustainable development and construction have led to the gradual deepening of the constraint degree of wood resources on wood processing enterprises. Third, due to the scarcity of resources, the increase in production costs such as procurement costs, storage costs and financing costs of wood raw materials brought about by enterprise production reduces the market price advantage of products and increases the operating pressure and risk of enterprises. Fourth, after the implementation of the natural forests stop-logging policy, the resource constraints in the state-owned forest areas of Northeast China is still at a higher level on the whole, although it is lower than the two crisis periods. (4) Conclusions and Discussions--The transformation paths of enterprises are analyzed from three aspects: diversified development, digital development and marketization development. Several policy recommendations are put forward for different types of wood processing enterprises: First, the wood processing enterprises that rely heavily on wood imports should actively carry out the construction of transportation networks to save transportation costs. Second, the state-owned wood processing enterprises should drive the main business with diversified management and guide the intervention of non-forestry capital to stimulate innovation. Third, small and medium-sized, primary wood processing enterprises should pay attention to improving the degree of agglomeration, in order to play the advantages of cluster. Fourth, wood-based panel processing enterprises and wood products processing enterprises should adopt digital means and integrate intelligent manufacturing in order to improve product quality on the basis of sustainable development. Fifth, the private wood processing enterprises should find the right market positioning based on public demands, in order to improve added value of products and market competitiveness and promote the steady development of enterprises. [ABSTRACT FROM AUTHOR]

Let G be a simple graph with vertex set V (G) and edge set E (G). For x ∈ V (G) , let N G (x) = { y ∈ V (G) | x y ∈ E (G) } and N G (X) = ⋃ x ∈ X N G (x). For X ⊆ V (G) , the number d (X) ≔ | X | − | N G (X) | is called difference of X and critical difference of G denoted by d c (G) is max { d (X) ∣ X ⊆ V (G) }. A set S ⊆ V (G) is a critical independent set if S is an independent set and d (S) = d c (G). Zhang (1990) proved that for every graph, there exists an independent set attaining the critical difference. Let Λ 0 (G) denote the family of all nonempty critical independent sets of G. If α (G) + μ (G) = | V (G) | , then G is called a König–Egerváry graph, where α (G) and μ (G) denote independence number and matching number of G , respectively. We define k e r 0 (G) to be the intersection of all sets in Λ 0 (G) and c o r e (G) to be the intersection of all maximum independent sets. In this paper, we characterize König–Egerváry graphs satisfying k e r 0 (G) = c o r e (G) in terms of Gallai–Edmonds Structure Theorem. As a corollary of this result, we solve an open problem posed by Jarden et al. (2018). [ABSTRACT FROM AUTHOR]

Introduction: It is clear that mental fatigue can have many negative impacts on individuals, such as impairing cognitive function or affecting performance. The aim of this study was to investigate the role of sound interventions in combating mental fatigue. Method: The subjects were assessed on various scales, a psychomotor vigilance task (PVT) task, and a 3 min resting-state electroencephalogram (EEG), followed by a 20 min mental fatigue–inducing task (Time Load Dual Back, TloadDback), during which subjects in different condition groups listened to either 15 Hz binaural beats, 40 Hz binaural beats, relaxing music, or a 240 Hz pure tone. After the mental fatigue–inducing task, subjects were again assessed on various scales, a PVT task, and a 3 min resting-state EEG. Results: After the fatigue-inducing task, there was no significant difference between the four groups on the scales or the PVT task performance. In TloadDback, the accuracy rate of the 40 Hz binaural beats group and the relaxing music group decreased in the middle stage of the task, while the 15 Hz binaural beats group and the 240 Hz pure tone group remained unchanged in all stages of the task. The EEG results showed that after fatigue inducement, the average path length of the 15 Hz binaural beats group decreased, and local efficiency showed an increasing tendency, indicating enhanced brain network connectivity. Meanwhile, the 240 Hz pure tone group showed enhanced functional connectivity, suggesting a state of mental fatigue in the group. Conclusions: The results of this study show that listening to 15 Hz binaural beats is a proven intervention for mental fatigue that can contribute to maintaining working memory function, enhancing brain topological structure, and alleviating the decline in brain function that occurs in a mentally fatigued state. As such, these results are of great scientific and practical value. [ABSTRACT FROM AUTHOR]

Synthetic aperture radar (SAR) tomography (TomoSAR) has been widely used in the three-dimensional (3D) reconstruction of urban areas using the multi-baseline (MB) SAR data. For urban scenarios, the MB SAR data are often acquired by repeat-pass using the spaceborne SAR system. Such a data stack generally has long time baselines, which result in different atmospheric disturbances of the data acquired by different tracks. These factors can lead to the presence of phase errors (PEs). PEs are multiplicative noise for observation data, which can cause diffusion and defocus in TomoSAR imaging and seriously affect the extraction of target 3D information. In this paper, we combine the methods of the block-building network (BBN) and phase gradient autofocus (PGA) to propose a novel phase compensation method called BBN-PGA. The BBN-PGA method can effectively and efficiently compensate for PEs of the MB SAR data over a wide area and improve the accuracy of 3D reconstruction of urban areas. The applicability of this proposed BBN-PGA method is proved by using simulated data and the spaceborne MB SAR data acquired by the TerraSAR-X satellite over an area in Barcelona, Spain. [ABSTRACT FROM AUTHOR]

This article presents a high‐precision modeling method to build a small signal model of GaAs pseudomorphic high electron mobility transistor (pHEMT) by using a radial basis function artificial neural network (RBF ANN). Both the RBF ANN Method 1 that uniformly distributed spread constant (SC) in the given range and Method 2 that increasingly changed SC with a chosen step have been modeled in this work. Compared with the l RBF ANN Method 1, the RBF ANN method 2 can automatically obtain the optimal ANN corresponding to the SC. The RBF ANN method 2 is developed for S‐parameters model and equivalent circuit parameters (ECPs) model of HEMTs. S‐parameters model establishes S‐parameters versus bias, temperature and frequency, while the ECPs model establishes ECPs versus bias and temperature. To validate the capability of the RBF ANN in small signal modeling of GaAs pHEMTs, measured and modeled data of S‐parameters model and ECPs model of a 4 × 75 μm gate width, 0.15 μm gate length GaAs pHEMT are compared, and very good agreement is achieved up to 50 GHz. For the S‐parameters model, the average error of the method 2 is improved by about 20% at the temperature of −20°C, 25°C, and 85°C. For the ECPs model, the average error of the method 2 is 80% higher than that of the method 1. [ABSTRACT FROM AUTHOR]

Given a positive integer r, let [ r ] = { 1 , … , r } . Let n, m be positive integers such that n is sufficiently large and 1 ≤ m ≤ ⌊ n / 3 ⌋ - 1 . Let H be a 3-graph with vertex set [n], and let δ 1 (H) denote the minimum vertex degree of H. The size of a maximum matching of H is denoted by ν (H) . Kühn, Osthus and Treglown (2013) proved that there exists an integer n 0 ∈ N such that if H is a 3-graph with n ≥ n 0 vertices and δ 1 (H) > n - 1 2 - n - m 2 , then ν (H) ≥ m . In this paper, we show that there exists an integer n 1 ∈ N such that if | V (H) | ≥ n 1 , δ 1 (H) > n - 1 2 - n - m 2 + 3 and ν (H) ≤ m , then H is a subgraph of H ∗ (n , m) , where H ∗ (n , m) is a 3-graph with vertex set [n] and edge set E (H ∗ (n , m)) = { e ⊆ [ n ] : | e | = 3 and e ∩ [ m ] ≠ ∅ } . The minimum degree condition is best possible. [ABSTRACT FROM AUTHOR]

Rödl, Ruciński, and Szemerédi determined the minimum (k - 1) -degree threshold for the existence of fractional perfect matchings in k-uniform hypergrahs, and Kühn, Osthus, and Townsend extended this result by asymptotically determining the d-degree threshold for the range k - 1 > d ≥ k / 2 . In this note, we prove the following exact degree threshold: let k, d be positive integers with k ≥ 4 and k - 1 > d ≥ k / 2 , and let n be any integer with n ≥ 2 k (k - 1) + 1 . Then any n-vertex k-uniform hypergraph with minimum d-degree δ d (H) > n - d k - d - n - d - (⌈ n / k ⌉ - 1) k - d contains a fractional perfect matching. This lower bound on the minimum d-degree is best possible. We also determine the minimum d-degree threshold for the existence of fractional matchings of size s, where 0 < s ≤ n / k (when k / 2 ≤ d ≤ k - 1 ), or with s large enough and s ≤ n / k (when 2 k / 5 < d < k / 2 ). [ABSTRACT FROM AUTHOR]

Maternal egg‐caring behavior can often be observed in oviparous scincid lizards. The expression of such behavior is predictably affected by the trade‐off between its resultant costs and benefits for mothers and/or offspring, which has been investigated in only a few scincid species. Here, post‐ovipositional Plestiodon chinensis females were treated to care for their egg clutches without interference, under simulated predation pressure, or to be care‐deprived. Potential maternal costs and offspring benefits associated with egg‐caring behavior were then evaluated by measuring changes in maternal body condition, egg mortality, and hatchling performance. Egg‐caring behavior caused post‐ovipositional females to participate less in outside‐nest activity, eat less food, and show relatively poorer body conditions at egg hatching. By contrast, compared with care‐deprived females, egg‐caring females gained mass slightly faster, and achieved a similar body condition within a few months of hatching. Eggs that were cared for by their mothers were more likely to hatch and produced larger, faster‐running and better‐growing hatchlings with higher survival than uncared‐for eggs. Simulated exposure to a potential predator had no distinct impact on maternal egg‐caring behavior expression and offspring performance. These results indicated that marked benefits of offspring viability but minor maternal energy costs might play a decisive role in the occurrence of maternal egg‐caring behavior in P. chinensis. [ABSTRACT FROM AUTHOR]

In this article, a semiempirical equivalent circuit model of the grounded coplanar waveguide (GCPW) based on the vector fitting is proposed for the first time, which improves the accuracy in high frequency. It offers an effective solution for the millimeter GCPW modeling. This model takes into account nonideal effects such as skin effect and substrate coupling effect, which realizes the combination of numerical method and physical meaning. The method we propose aims to use sequential quadratic programming algorithm to solve strictly passive problems. Good agreement is obtained between the modeled and measured data up to 40 GHz. [ABSTRACT FROM AUTHOR]

Let r ≥ 3 be an integer and G be a graph. Let δ (G) , Δ (G) , α (G) , and μ (G) denote the minimum degree, maximum degree, independence number, and matching number of G , respectively. Recently, Caro, Davila and Pepper proved δ (G) α (G) ≤ Δ (G) μ (G). Mohr and Rautenbach characterized the extremal graphs within the classes of all non-regular graphs and 3-regular graphs. In this note, we characterize the extremal graphs within the classes of all r -regular graphs in terms of the Gallai–Edmonds Structure Theorem, which extends Mohr and Rautenbach's result. [ABSTRACT FROM AUTHOR]

We mimicked daily fluctuations in temperature to examine whether the magnitude of the incubation temperature fluctuation affected the immunity of Chinese soft‐shelled turtle (Pelodiscus sinensis) hatchlings. The control incubation temperature was 29℃. Two of the temperatures used (29℃ ± 3℃ and 29℃ ± 5℃) were within the optimal range of the turtle's constant incubation temperature, and one (29℃ ± 9℃) was outside of this range. Data on hatching success, incubation period, and weight of the turtle hatchlings were collected. The incubation period and hatchling weight were significantly affected by temperature fluctuation, whereas the hatching success was not. After two months, the effect of the temperature fluctuation on hatchling weight was much more pronounced. After challenging hatchlings with pathogens, the hatchlings from the extremely fluctuating incubation temperature group were feeble. To explore the molecular changes of immunity associated with incubation temperature, serum lysozyme, acid and alkaline phosphatase activities, and seven immune‐related genes were examined in two‐month‐old turtles. Before pathogen infection, serum lysozyme activities were lower in turtles that experienced fluctuating temperature, and serum acid and alkaline phosphatase activities were higher in turtles exposed at 29℃ ± 3℃ and 29℃ ± 5℃. After pathogen challenge, lysozyme responded to the pathogen infection in 12 h, and acid and alkaline phosphatase activities were lower at 12 and 48 h in all four groups. Although the expression of the seven immune‐related genes was not affected before the bacterial challenge, they were upregulated after the bacterial challenge in all four groups. [ABSTRACT FROM AUTHOR]

Objectives: In this study, we describe a newly excavated early Holocene human cranium from Guizhou, Southwestern China, namely the Zhaoguo M1 (ZG 1). We aim to evaluate its morphological resemblance with Late Pleistocene human, and Northern and Southern China Neolithic populations. We also aim to infer its position in the process of East Asian population regionalization. Materials and Methods: The ZG 1 skull is almost complete, only missing parts of the right parietal and the basicranium around the foramen magnum. Comparative samples include Late Pleistocene humans and Neolithic populations from Northern and Southern China. Univariate and multivariate analyses are carried out in the study. Results: ZG 1 has a dolichocephalic cranium, wide zygomatic breadth, moderate glabella and supraobtial projection, marked canine fossa, and thin cranial vault. The nasal floor, maximum cranial breadth position, and frontal arc proportion are all congruent with modern human. Statistical analysis suggests that ZG 1's measurements are most similar to those of Southern China Neolithic specimens, with some closer to Late Pleistocene humans. Conclusion: ZG 1 shows a clear affinity with Southern China Neolithic populations, providing further support that regionalization of morphological variability patterns between Northern and Southern Neolithic populations could have originated at least 10,000 years ago. [ABSTRACT FROM AUTHOR]

A two-dimensional electron gas (2DEG) was formed at the interface of an ultrathin ZnO/Ga2O3 heterostructure deposited by atomic layer deposition (ALD) at 200 °C on a SiO2/Si substrate. It is found that the sheet resistance decreases steeply to ∼104 Ω/□ as the thickness of the ZnO layer increases to a certain extent, and an optimal thickness of the top layer is determined. An ∼50-nm-thick β-phase Ga2O3 layer was formed after annealing at 800 °C, and a 12-nm-thick amorphous ZnO layer was observed by x-ray diffraction and transmission electron microscopy. The oxygen defects were analyzed by x-ray photoelectron spectroscopy. The defect energy levels of oxygen vacancies in Ga2O3 and ZnO thin films were calculated by first-principles simulation, and oxygen vacancies were generated at the interface of the ZnO/Ga2O3 thin film heterostructure to form 2DEG, which is demonstrated experimentally and theoretically. An assumption is proposed that the oxygen vacancy plays a role of the donor of free electrons at the ZnO/Ga2O3 interface because of the small energy level between the oxygen vacancy defect level and conduction band minimum (CBM) of the ZnO layer, which could easily trigger the charge transfer in the interface region. The 2DEG can be realized on the partially ordered microstructure of the Ga2O3 layer. With the assistance of the ALD technique, the thickness of the ZnO/Ga2O3 heterostructure can be as thin as ∼65 nm, which is favorable for devices of stack or ultrathin structures. Moreover, the low temperature deposition by ALD can be adopted for flexible or stretchable devices. [ABSTRACT FROM AUTHOR]

A graph G has the strong parity property if for every subset X ⊆ V (G) with |X| even, G has a spanning subgraph F with minimum degree at least one such that d F (v) ≡ 1 (mod 2) for all v ∈ X , d F (y) ≡ 0 (mod 2) for all y ∈ V (G) - X . Bujtás et al. (Graphs Combin 36(2020):1391–1399, 2020) introduced the concept and conjectured that every 2-edge-connected graph with minimum degree at least three has the strong parity property. In this paper, we give a characterization for graphs to have the strong parity property and construct a counterexample to disprove the conjecture proposed by Bujtás, Jendrol' and Tuza. [ABSTRACT FROM AUTHOR]

Synthetic aperture radar (SAR) tomography (TomoSAR) has been well-established for three-dimensional (3-D) information extraction of forests using the multi-baseline SAR data stacks. The multi-baseline SAR data stacks can be acquired by spaceborne and airborne SAR systems, but for forest scenarios, the data stacks acquired by the airborne SAR system are mostly used. Such a data stack has the advantages of short revisiting time and weak temporal decorrelation. However, due to the baseline errors (caused by the residual platform motion and the measurement errors of the navigation instruments), phase errors (PEs) will occur. PEs are independent of one track to the other, resulting in spreading and defocusing in tomographic imaging. In this paper, we proposed a novel phase compensation method named NC-PGA, which combines the methods of network construction (NC) and phase gradient autofocus (PGA) to estimate and compensate the PEs. The NC method uses the Delaunay triangulation network and beamforming to obtain an accurate elevation estimate of the selected permanent scatterers, which can be used as the prior information for subsequent processing to overcome the shortcomings of the PGA method in PEs estimation. The PGA method uses the spatial invariance of PEs in a limited area to compensate for the PE of each track. The applicability of the NC-PGA method is demonstrated using simulated data and real data. The real data contains two data stacks. The one is acquired by a full-polarization P-band airborne SAR system (developed independently by our project research team) over the study area in Saihanba Forest Farm in Hebei, China. The other one is acquired by ONERA SETHI airborne system over Paracou, French Guiana, in the frame of the European Space Agency's campaign TropiSAR. We select a test area in the study area and successfully retrieve the height of the forest, and use LiDAR data for results validation and evaluation. [ABSTRACT FROM AUTHOR]

• We created a novel experimental paradigm combining multibrain noninvasive stimulation with fNIRS hyperscanning to study human coordination. • The neural modulation induced by multibrain noninvasive stimulation enhanced coordination behavior, providing direct evidence of a causal link between neural activity and coordination behavior. • Improved interbrain synchronization of task states and enhanced neural efficiency in cortical areas related to the mirror neuron system had a positive impact on coordination performance. • The behavioral benefits of interbrain synchronization were long lasting. • Applications of these two interventions (hyper-tACS/hyper-tDCS) for enhancement of coordination should be guided by their temporal sensitivity. Coordination is crucial for individuals to achieve common goals; however, the causal relationship between coordination behavior and neural activity has not yet been explored. Interbrain synchronization (IBS) and neural efficiency in cortical areas associated with the mirror neuron system (MNS) are considered two potential brain mechanisms. In the present study, we attempted to clarify how the two mechanisms facilitate coordination using hypertranscranial electrical stimulation (hyper-tES). A total of 124 healthy young adults were randomly divided into three groups (the hyper-tACS, hyper-tDCS and sham groups) and underwent modulation of the right inferior frontal gyrus (IFG) during functional near-infrared spectroscopy (fNIRS). Increased IBS of the PFC or neural efficiency of the right IFG (related to the MNS) was accompanied by greater coordination behavior; IBS had longer-lasting effects on behavior. Our findings highlight the importance of IBS and neural efficiency of the frontal cortex for coordination and suggest potential interventions to improve coordination in different temporal windows. [Display omitted] [ABSTRACT FROM AUTHOR]

• Human-like decision making that considers both control and optimization is proposed for human-like ADS. • An HRL-based decision-making framework that integrates cognitive map and MP is proposed for human-like lane change. • An SR-based cognitive map is introduced to serve as the decision belief to guide human-like decision making. Human-like decision making is crucial to developing an autonomous driving system (ADS) with high acceptance. Inspired by the cognitive map, this paper proposes a hierarchical reinforcement learning (HRL)-based framework with sound biological plausibility named Cog-MP, which combines the cognitive map and motion primitive (MP) in human-like decision making. In the proposed Cog-MP, three general levels involved in ADS are integrated in a top–bottom way, including operational, decision-making, and cognitive levels. The proposed Cog-MP is used to make human-like decisions in lane-changing scenarios, focusing on three aspects: human-like lane decision, human-like path decision, and decision optimization. The proposed framework is validated on two groups of realistic lane-change data, of which one group is used to train cognitions towards different styles of driving behaviors, and the other group is to provide validation scenarios. Experimental results show that the proposed framework can generate human-like decisions and perform soundly regarding the three considered aspects, demonstrating a promising prospect in developing a brain-inspired human-like ADS. [ABSTRACT FROM AUTHOR]

Objectives: Aims of the study are to initially describe and comparatively evaluate the morphology of the new Zhaoguo M1 upper limb remains, and contextualize upper limb functional adaptations among those of other worldwide Upper Paleolithic (UP) humans to make inferences about subsistence‐related activity patterns in southwestern China at the Pleistocene–Holocene boundary. Materials and methods: The preserved Zhaoguo M1 skeletal remains include paired humeri, ulnae, and radii, among others. These specimens were scanned using micro‐computed tomography to evaluate internal structural properties, while external osteometric dimensions of the Zhaoguo M1 upper limb elements also were acquired. Both sets of measurements were compared to published data on Neandertals, and Middle and Upper Paleolithic modern humans. Results: The upper limb elements of Zhaoguo M1 display a suite of characteristics that generally resemble those of other contemporary Late UP (LUP) modern humans, while robusticity indices generally fall within the upper range of LUP variation. The Zhaoguo M1 upper limb elements display fewer traits resembling those of late archaic humans. The Zhaoguo M1 individual exhibits diaphyseal asymmetry in several upper limb elements suggesting left hand dominance. When evaluating the full range of magnitudes of humeral bilateral asymmetry in the comparative sample, Zhaoguo M1 falls at the lower end overall, but yet is relatively higher than contemporary LUP modern humans specifically from East Eurasia. Discussion The Zhaoguo M1 individual suggests typical LUP modern human upper limb morphology persisted in southwest China until the end of the last glacial period. Upper limb bone asymmetry of Zhaoguo M1 also indicates that behavioral activities attributed to a hunter‐gatherer tradition apparently extended through the Pleistocene–Holocene transition in this region. [ABSTRACT FROM AUTHOR]

A novel vertical graded source tunnel field-effect transistor (VGS-TFET) is proposed to improve device performance. By introducing a source with linearly graded component, the on-state current increases by more than two decades higher than that of the conventional GaAs TFETs without sacrificing the subthreshold swing (SS) due to the improved band-to-band tunneling efficiency. Compared with the conventional TFETs, much larger drive current range can be achieved by the proposed VGS-TFET with SS below the thermionic limitation of 60 mV/dec. Furthermore, the minimum SS about 20 mV/dec indicates its promising potential for further ultralow power applications. [ABSTRACT FROM AUTHOR]

Temperature is a crucial environmental factor that can strongly impact animal physiology. Here, we acclimated hatchling of Asian yellow pond turtles (Mauremys mutica) to one of two different temperatures (25 or 30°C) for four weeks to determine temperature acclimation effects on their physiology. All four measured physiological variables (righting time, resting metabolic rate, critical thermal minimum and critical thermal maximum) were significantly affected by temperature acclimation. Turtles acclimated to 25°C righted themselves more slowly and had a lower mean metabolic rate than 30°C-acclimated turtles. Turtles acclimated to 25°C were more resistant to low temperatures, but less resistant to high temperatures than 30°C-acclimated turtles, as measured by critical thermal limits. The thermal resistance range (i.e., the difference between critical thermal minimum and maximum) did not differ between the two acclimation groups. Compared with other semi-aquatic turtles, M. mutica had relatively higher acclimation response ratios for its critical thermal minimum and critical thermal maximum. Our results indicate that acclimation to relatively moderate temperatures could also produce significant responses in the thermal physiology of turtles. [ABSTRACT FROM AUTHOR]

Let H be a k‐partite k‐graph with n vertices in each partition class, and let δk−1(H) denote the minimum codegree of H. We characterize those H with δk−1(H)≥n∕2 and with no perfect matching. As a consequence, we give an affirmative answer to the following question of Rödl and Ruciński: if k is even or n≢2(mod4), does δk−1(H)≥n∕2 imply that H has a perfect matching? We also give an example indicating that it is not sufficient to impose this degree bound on only two types of (k−1)‐sets. [ABSTRACT FROM AUTHOR]

The effect of traps to C–V and I–V plots of InP/InGaAs heterostructure with 3 MeV proton irradiation at different fluences has been discussed. After proton irradiation, the total reverse capacitance increases, which does not only include the variation of the depletion region width, but also the charging and discharging effect of traps. The total actual traps density NSS of InP/InGaAs heterostructure could reach 13 orders of trap density, which is from the peak under reverse bias. The forward current is dominated by recombination current at low voltage and by the tunneling current at high voltage. The tunneling current and trap-assisted tunneling current are dominant in the reverse current. [ABSTRACT FROM AUTHOR]

This article presents a radiation-hardened voltage reference and a radiation-hardened low-dropout (LDO) voltage regulator manufactured in bipolar technology for space environment applications. The output of voltage reference is adjustable in 2.5 V ∼ 30 V, with a supply voltage of 24 V. The LDO regulator operates from an input voltage range of 2.5–26 V and provides an output voltage of 1.5 V, with output voltage accuracy of ±0.5 %. The dropout voltage <700 mV at the full load current of 7A. It achieves line regulation and load regulation are <0.5 % over the entire operating temperature range. Through the circuit design of radiation hardening and the optimization of anti-radiation technology, both power management chips have single-event transient (SET) immunity at linear energy transfer (LET) of 37.4 MeV·cm2/mg. The output voltage deviation of rad-hard voltage reference is <0.6 % with total dose radiation tolerance of 100krad(Si) at 0.1 rad(Si)/s. • A radiation-hardened voltage reference for space environment applications. • A radiation-hardened low-dropout (LDO) regulator for space applications. • Circuit design and process optimization hardening (Design-Technology-Co-Hardening). [ABSTRACT FROM AUTHOR]

In this study, we present the preliminary result of archaeobotanical investigation at Kaerdong in western Tibet. The result shows that agropastoralism with combined strategies of foraging, hunting and fishing was in practice at the location between approximately 455 and 700 cal. AD. Our results also show that herding animals grazed at meadows above 4300 m above sea level (masl), and dung was used as fuel. The presence of a rice grain together with spikelet bases indicates that rice was a component of food resources possibly as a result of a trade and exchange system. In addition, tatary buckwheat grains were also recovered at the site. [ABSTRACT FROM AUTHOR]

In this paper, a universal analytical current model for a double-gate Si-based tunnel field-effect transistor (TFET) is presented considering the effects of charges in source depletion region and channel. An accurate surface potential model is developed first by solving the pseudo-2-D Poisson equations in the depletion regions, and then is used to calculate the drain tunneling current. The modeling results match well with that obtained from the Technology computer-aided design simulations under various biasing conditions, which indicate that the analytical current model would be very helpful for the further TFET-based circuits design. Furthermore, the influence of the source depletion is also studied, and the presented model with considering the source depletion region and the channel inversion charges is proved to be much more accurate than that ignoring the source depletion. [ABSTRACT FROM AUTHOR]

Based on an analytical surface potential model incorporating the channel inversion carriers, a physics-based terminal capacitance model with closed-form solutions for a hetero-gate-dielectric (HGD) tunnel field-effect transistor (TFET) is developed for the first time. Good agreements between the proposed model and the numerical simulations have been achieved in all operation regimes and for different HGD structures. The developed model without involving any iterative process can be easily applied to the widely used SPICE simulations and would be helpful for the transient performance of TFET-based circuits. [ABSTRACT FROM AUTHOR]

Aharoni and Howard conjectured that, for positive integers n , k , t with n ≥ k t , if F 1 , ... , F t ⊆ ( [ n ] k ) such that | F i | > max ⁡ { ( n k ) − ( n − t + 1 k ) , ( k t − 1 k ) } for i ∈ [ t ] then there exist e i ∈ F i for i ∈ [ t ] such that e 1 , ... , e t are pairwise disjoint. Huang, Loh, and Sudakov proved this conjecture for t < n / (3 k 2). In this paper, we show that this conjecture holds for t < n / (2 k) and t sufficiently large. [ABSTRACT FROM AUTHOR]

Abstract: For a hypergraph H, let δ 1 ( H ) denote the minimum vertex degree in H. Kühn, Osthus, and Treglown proved that, for any sufficiently large integer n with n ≡ 0 ( mod 3 ), if H is a 3‐uniform hypergraph with order n and δ 1 ( H ) > n − 1 2 − 2 n / 3 2 then H has a perfect matching, and this bound on δ 1 ( H ) is best possible. In this article, we show that under the same conditions, H contains at least ⌈ ( 2 n + 3 ) / 9 ⌉ pairwise disjoint perfect matchings, and this bound is sharp. [ABSTRACT FROM AUTHOR]

Abstract: Temperature is one of most the important environmental factors that affect the ontogenesis of organisms. In this study, we incubated Chinese soft‐shelled turtle eggs at 28°C (control temperature, C treatment), a temperature with a 16°C cold shock and a 36°C heat shock twice per week (S treatment) or a ramp‐programmed temperature of 29 ± 9°C (with 12 hr (+) and 12 hr (−) every day) (F treatment). The incubation period, hatching success, hatchling weight, and locomotor performance were significantly different between the controls and the different heat treatment groups. The pathogen challenge results illustrated that hatchlings from the S treatment group were more resistant to bacterial infection, whereas hatchlings from the F treatment group were more vulnerable. We used RNA‐seq quantification analysis to identify differentially expressed genes (DEGs) of hatchlings in the S treatment group. Based on the functional annotation results for the DEGs, 9 genes were chosen to verify the RNA‐seq results. The background expression of DEGs was also analyzed for the three treatments, as was the regulation of the pathogen challenge. The results showed that 8 DEGs were related to the immune response after pathogen challenge and that temperature was an important factor in differential regulation of the immunity pathways. [ABSTRACT FROM AUTHOR]

Let a and b be two positive integers such that a ≤ b and a ≡ b ( mod 2 ) . A graph F is an ( a , b ) -parity factor of a graph G if F is a spanning subgraph of G and for all vertices v ∈ V ( F ) , d F ( v ) ≡ b ( mod 2 ) and a ≤ d F ( v ) ≤ b . In this paper we prove that every connected graph G with n ≥ b ( a + b ) ( a + b + 2 ) ∕ ( 2 a ) vertices has an ( a , b ) -parity factor if n a is even, δ ( G ) ≥ ( b − a ) ∕ a + a , and for any two nonadjacent vertices u , v ∈ V ( G ) , max { d G ( u ) , d G ( v ) } ≥ a n a + b . This extends an earlier result of Nishimura (1992) and strengthens a result of Cai and Li (1998). [ABSTRACT FROM AUTHOR]

Based on an analytical surface potential and a simple mathematical approximation for the source depletion width, a physics-based capacitance model with closed form for silicon double-gate tunnel field-effect transistors (TFETs) is developed. Good agreements between the proposed model and the numerical simulations have been achieved, which reveal that the tunneling carriers from source have negligible contribution to the channel charges and the gate capacitance can be almost acted as the gate–drain capacitance, which is quite different from that of MOSFETs. This model without involving any iterative process is more SPICE friendly for circuit simulations compared with the table-lookup approach and would be helpful for developing the transient performance of TFET-based circuits. [ABSTRACT FROM PUBLISHER]

For a hypergraph H , let δ 1 ( H ) denote the minimum vertex degree of H , and ν ( H ) denote the maximum size of a matching in H . For integers n ≥ m ≥ 1 , let d 3 ( n , m ) = n 2 − ( n − ⌊ m ∕ 3 ⌋ ) ( n − ⌊ ( m + 1 ) ∕ 3 ⌋ ) if m ≠ 1 ( m o d 3 ) , n 2 − ( n − ( m − 1 ) ∕ 3 ) 2 + 1 if m = 1 ( m o d 3 ) . Let H be a 3-partite 3-uniform hypergraph with n vertices in each partition class. Lo and Markström proved that there exists a positive integer N such that if n ≥ N and δ 1 ( H ) > d 3 ( n , n − 1 ) , then ν ( H ) > n − 1 . They also showed that if n ≥ 3 7 m and δ 1 ( H ) > d 3 ( n , m ) , then ν ( H ) > m , and asked whether the condition n ≥ 3 7 m can be replaced by n > m . In this note, we show that there exists a positive integer n 0 such that if n ≥ n 0 and δ 1 ( H ) > d 3 ( n , m ) , then ν ( H ) > m . [ABSTRACT FROM AUTHOR]

The problem of how many edge disjoint perfect matchings are there in a regular graph has attracted considerable interest. Most of the work focus on the case where the degree is large, roughly speaking, equal to half of the total number of the vertices in the graph. In this paper, we look at the case where the degree is smaller. Let n , k , m be three positive integers such that k = ⌊ ( n − 1 ) ∕ 2 ⌋ and m ≤ k , we show that every 2 k -regular m -edge-connected graph with 2 n vertices contains at least m edge-disjoint perfect matchings, and the condition on edge connectivity is sharp. [ABSTRACT FROM AUTHOR]

In this paper, reverse-biased gate leakage current in Al 2 O 3 /InAlAs metal-oxide-semiconductor (MOS) structures has been investigated. The current-voltage (I-V) characteristics were measured from 283 to 343 K with a step of 20 K. It is found that Schottky emission is dominant at low reverse bias (< 0.4 V). The dynamic dielectric constant of Al 2 O 3 and the Schottky barrier height determined by the linear fitting are 2.19 and 0.70 ± 0.01 eV, respectively. However, beyond the Schottky emission region, leakage current follows space charge limited (SCL) conduction. Trap-filled limited (TFL) conduction is observed at all the measurement temperatures, whereas Ohm's law is only observed at 343 K and transition between TFL conduction and Child's law is only observed at 323 and 343 K. This phenomenon could be ascribed to different transition conditions at different measurement temperatures. Besides, the potential well depth of traps (E c − E t ) calculated from TFL conduction is 0.40 ± 0.01 eV. [ABSTRACT FROM AUTHOR]

An Al 2 O 3 layer is inserted between the InAlAs layer and the metal gate in InAs/AlSb HEMTs to suppress the leakage current. The transport mechanisms of leakage current in Al 2 O 3 /InAlAs metal–oxide–semiconductor (MOS) capacitors at both positive and negative biases at different temperatures ranging from 10 °C to 70 °C are investigated. For positive bias, the leakage current is dominated by Schottky emission. Based on the fitted straight lines, the relative dielectric constant of Al 2 O 3 and the barrier height between Al 2 O 3 and InAlAs are extracted. However, for negative bias, the leakage current is dominated by Frenkel–Poole (F–P) emission and the depth of the trap energy level from the conduction band ( ϕ t ) is extracted. Furthermore, authors explain the reason why the dominating mechanisms at positive and negative biases are different. [ABSTRACT FROM AUTHOR]

Let G be a graph and n, k and d be non-negative integers such that $$|V(G)|\geqslant n+2k+d+2$$ and $$|V(G)|-n-d \equiv 0 \pmod {2}$$ . A graph is called an ( n, k, d)- graph if deleting any n vertices from G the remaining subgraph of G contains k-matchings and each k-matching in the subgraph can be extended to a defect- d matching. We study the relationships between ( n, k, d)-graphs and various closure operations, which are usually considered in the theory of hamiltonian graphs. In particular, we obtain some necessary and sufficient conditions for the existence of ( n, k, d)-graphs in terms of these closures. [ABSTRACT FROM AUTHOR]

• All the extrinsic parameters are determined by employing S-parameter measured only under cut-off and normal bias conditions. • The scaling rule for the intrinsic base-emitter capacitance and the parameter scanning method for the base–collector extrinsic capacitance are used to obtain all capacitance parameters. The extrinsic inductances and resistances are obtained by the direct extraction method. Finally, these more accurate parasitic values are used as the initial values for parameter optimization , and the optimal parasitic parameter values are obtained by fine-tuning. • The proposed method not only eliminates the critical measurement of the open-collector condition, but also greatly improves the efficiency and accuracy of parameter optimization. An improved parasitic parameters extraction method for InP heterojunction bipolar transistor (HBT) is developed. The difference between this method and previous methods is that all parasitic parameters can be extracted by relying only on the S-parameters measured under the cut-off and normal bias conditions. All the capacitance parameters in the equivalent circuit at the low-frequency cut-off can be extracted by combining the analytical closed formulas and the parameter scanning method. The intrinsic resistance R bi is obtained indirectly by extracting the extrinsic resistance R e based on the Z-parameter method in the normal bias conditions. By de-embedding the parasitic capacitances, all the values of parasitic inductances and extrinsic resistances are obtained by the direct extraction method under the cut-off condition. The proposed method not only eliminates the critical measurement of the open-collector condition, but also greatly improves the efficiency and accuracy of parameter optimization. For different sizes and bias conditions of InP HBT devices, the excellent agreement between simulated and measured results is verified all over the frequency range of 0.4–50 GHz. [ABSTRACT FROM AUTHOR]

Temperature-dependent DC and small-signal analysis have been carried out on 0.7 μm × 15 μm InGaAs/InP double heterojunction bipolar transistors over a temperature range of 25 °C–125 °C by on-wafer S -parameter measurements up to 50 GHz. The thermal behavior of DC and equivalent circuit parameters along with their temperature coefficients were analyzed and reported for the first time using the same InP-based DHBT. Most of the DC parameters show a negative with temperature, for example the temperature coefficients of the V BE,on and V BC,on are −1.4 and −1.48 mV/°C, respectively. And the peak current gain declined from 44.04 to 36.09 with the temperature increased from 25 °C to 125 °C. On the other hand, most of the small-signal parameters show a positive trend with temperature, except for the intrinsic base resistance R bi , intrinsic base–collector capacitance C bc , intrinsic base–emitter capacitance C be , and common-base current transport factor α 0. The results will provide valuable references and insights for future design optimizations of temperature susceptible circuits. [ABSTRACT FROM AUTHOR]

Let G be a graph with vertex set V (G) and let H : V (G) → 2N be a set function associated with G. An H-factor of graph G is a spanning subgraphs F such that dF (v) ⅀ H(v) for every v ⅀ V (G). Let f : V (G) → N be an even integer-valued function such that f ≥ 4 and let Hf (v) = {1, 3, . . ., f (v) - 1, f (v)} for v ⅀ V (G). In this article, we investigate Hf -factors of graphs by using Lov' asz's structural descriptions. Let o(G) denote the number of odd components of G. We show that if one of the following conditions holds, then G contains an Hf -factor. (i) |V (G)| is even and o(G - S) ≤ f (S) for all S ⊆ V (G); (ii) |V (G)| is odd, dG(v) ≥ f (v) - 1 for all v ⅀ V (G) and o(G - S) ≤ f (S) for all ∅ ≠ S ⊆ V (G). As a corollary, we showthat if a graph G of odd order withminimum degree at least 2n - 1 satisfies o(G - S) ≤ 2n|S| for all ∅ ≠ S ⊆ V (G), then G contains an Hn-factor, where Hn = {1, 3, . . ., 2n - 1, 2n}. In particular, we make progress on the characterization problem for a special family of graphs proposed by Akiyama and Kano. [ABSTRACT FROM AUTHOR]

The physiological characteristics and survival of ectotherms are significantly influenced by the environmental temperature. Heat shock proteins (Hsps) are the primary molecular factors that are associated with ectotherm thermal adaption. Heat shock protein 70 (Hsp70) is an important Hsp family member that is involved in many aspects of protein homeostasis and in the immune response. In this study, an inducible Hsp70 homologue ( PsHsp70 ) from the soft-shelled turtle Pelodiscus sinensis was analysed at the molecular level. The recombinant PsHsp70 was purified from Escherichia coli and showed apparent ATPase activity by spectrophotometric assay. The constitutive expression of PsHsp70 was detected in the muscle, liver, kidney, brain, heart and lung by expression assay. The PsHsp70 expression pattern slightly differed in hatchlings incubated at 26 °C, 28 °C, and 30 °C. However, bacterial pathogens induced different levels of PsHsp70 expression in the livers of hatchlings incubated at 26 °C, 28 °C, and 30 °C. Under the harsh temperature of 34 °C, the overexpression of PsHsp70 in the pIRES2-EGFP plasmid in turtle embryos did not significantly affect the survival rate of either hatchlings or two-month-old turtles; however, the lysozyme activity significantly differed between hatchlings and two-month-old turtles before bacterial challenge, and the lysozyme activity of both hatchlings and two-month-old turtles changed significantly after bacterial challenge. Taken together, these results suggest that PsHsp70 may play a role in coping with environmental and biological stresses and may be involved in the immune response. [ABSTRACT FROM AUTHOR]

This paper is concerned with the surface embedding of matching extendable graphs. There are two directions extending the theory of perfect matchings, that is, matching extendability and factor-criticality. In solving a problem posed by Plummer, Dean (1992) established the fascinating formula for the minimum number k = μ ( Σ ) such that every Σ -embeddable graph is not k -extendable. Su and Zhang, Plummer and Zha found the minimum number n = ρ ( Σ ) such that every Σ -embeddable graph is not n -factor-critical. Based on the notion of ( n , k ) -graphs which associates these two parameters, we found the formula for the minimum number k = μ ( n , Σ ) such that every Σ -embeddable graph is not an ( n , k ) -graph. To access this two-parameter-problem, we consider its dual problem and find out μ ( n , Σ ) conversely. The same approach works for rediscovering the formula of the number ρ ( Σ ) . [ABSTRACT FROM AUTHOR]

A rigorous and systematic analytical-based parameter extraction technique for the augmented small-signal equivalent-circuit model dedicated to III-V-based heterojunction bipolar transistors (HBTs) is presented. The proposed extraction method relies exclusively on S -parameters measured at low and high frequencies. The extraction algorithm is derived by peeling peripheral elements from the small-signal equivalent circuit with very few simplified approximations throughout the whole extraction process. All of the elements' parameters of the small-signal equivalent-circuit model considering the base-collector and base-emitter capacitances distributed effect are determined accurately through the developed extraction technique. Excellent agreement is obtained demonstrating the comparisons between the small-signal S -parameters measured and modeled results for 0.7 μm InGaAs/InP HBTs over a wide range of bias points within the frequency range of 0.1–40 GHz, which verifies the validity and the accuracy of this model and extraction technique. [ABSTRACT FROM AUTHOR]